Memory cells having a number of conductive diffusion barrier materials and manufacturing methods

ABSTRACT

Memory cells having a select device material located between a first electrode and a second electrode, a memory element located between the second electrode and a third electrode, and a number of conductive diffusion barrier materials located between a first portion of the memory element and a second portion of the memory element. Memory cells having a select device comprising a select device material located between a first electrode and a second electrode, a memory element located between the second electrode and a third electrode, and a number of conductive diffusion barrier materials located between a first portion of the select device and a second portion of the select device. Manufacturing methods are also described.

PRIORITY INFORMATION

This application is a Divisional of U.S. application Ser. No. 13/952,162filed Jul. 26, 2013, the specification of which is incorporated hereinby reference.

TECHNICAL FIELD

The present disclosure relates generally to semiconductor memoryapparatuses and methods, and more particularly to resistance variablememory cells having a number of conductive diffusion barrier materialsand manufacturing methods.

Memory devices are utilized as non-volatile memory for a wide range ofelectronic applications in need of high memory densities, highreliability, and data retention without power. Non-volatile memory maybe used in, for example, personal computers, portable memory sticks,solid state drives (SSDs), digital cameras, cellular telephones,portable music players such as MP3 players, movie players, and otherelectronic devices.

Memory devices are typically provided as internal, semiconductor,integrated circuits in computers or other electronic devices. There aremany different types of memory, including random-access memory (RAM),read only memory (ROM), dynamic random access memory (DRAM), synchronousdynamic random access memory (SDRAM), flash memory, and resistancevariable memory, among others. Types of resistance variable memoryinclude phase change random access memory (PCRAM) and resistive randomaccess memory (RRAM), for instance.

Resistance variable memory devices, such as PCRAM devices, can include aresistance variable material, e.g., a phase change material, forinstance, which can be programmed into different resistance states tostore data. The particular data stored in a phase change memory cell canbe read by sensing the cell's resistance e.g., by sensing current and/orvoltage variations based on the resistance of the phase change material.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram of a portion of an array of memory cells 106in accordance with a number of embodiments of the present disclosure.

FIG. 2 illustrates a cross-sectional view of a memory cell in accordancewith a number of embodiments of the present disclosure.

FIG. 3 illustrates a cross-sectional view of a memory cell in accordancewith a number of embodiments of the present disclosure.

FIG. 4 illustrates a cross-sectional view of a memory cell in accordancewith a number of embodiments of the present disclosure.

DETAILED DESCRIPTION

Memory cells having number of conductive diffusion barrier materials andmethods of manufacturing the same are described herein. As an example, amemory cell can include a select device material located between a firstelectrode and a second electrode, a memory element located between thesecond electrode and a third electrode, and a number of conductivediffusion barrier materials located between a first portion of thememory element and a second portion of the memory element.

Memory cells, such as memory cells having a phase change material, canbe utilized in applications where a voltage is applied to the memorycell. This application of voltage can lead to electromigration, e.g.,during transition from an amorphous state to a crystalline state, ofcomponents of the phase change material. Due to this electromigration,the phase change material can segregate into insulating-type section anda conducting-type section prior to crystallization. This phase changematerial segregation can result in diffusion limited set statecrystallization. Diffusion limited set state crystallization canundesirably result in a portion of the phase change material fallingbelow a holding voltage or becoming too resistive such that the bitquenches without a full set into an intermediate resistance,non-crystalline state. Additionally, memory cells, such as memory cellshaving a phase change material, can be formed by a process that includesa hard mask deposition. Temperatures associated with the hard maskdeposition can be greater than a crystallization temperature of thephase change material. As such, the hard mask deposition can crystallizea portion of the phase change material prior to cell definition. Thiscrystallization can lead to phase segregation into grains larger thanthe dimension of the cell, resulting in non-homogenous memory cellcomposition across an array of memory cells.

As mentioned, embodiments of the present disclosure can provide memorycells having number of conductive diffusion barrier materials. Thenumber of conductive diffusion barrier materials can act as a diffusionbarrier to help prevent electromigration of components of a phase changematerial and/or modulate the grain size of the phase change material toprovide a homogenous memory cell composition across an array of memorycells. As such, embodiments can provide improved memory cells and/orarrays as compared to other approaches, among other benefits.

In the following detailed description of the present disclosure,reference is made to the accompanying drawings that form a part hereof,and in which is shown by way of illustration how a number of embodimentsof the disclosure may be practiced. These embodiments are described insufficient detail to enable those of ordinary skill in the art topractice the embodiments of this disclosure, and it is to be understoodthat other embodiments may be utilized and that process, electrical,and/or structural changes may be made without departing from the scopeof the present disclosure.

The figures herein follow a numbering convention in which the firstdigit or digits correspond to the drawing figure number and theremaining digits identify an element or component in the drawing.Similar elements or components between different figures may beidentified by the use of similar digits. For example, 106 may referenceelement “6” in FIG. 1, and a similar element may be referenced as 206 inFIG. 2. Also, as used herein, “a number of” a particular element and/orfeature can refer to one or more of such elements and/or features.

FIG. 1 is a block diagram of a portion of an array 100 of memory cells106 in accordance with a number of embodiments of the presentdisclosure. The array 100 can be a two terminal cross-point array havingmemory cells 106 located at the intersections of a first plurality ofconductive lines, e.g., access lines, 102-0, 102-1, . . . , 102-N, whichmay be referred to herein as word lines, and a second plurality ofconductive lines, e.g., data/sense lines, 104-0, 104-1, . . . , 104-M,which may be referred to herein as bit lines. The designators N and Mcan have various values. Embodiments are not limited to a particularnumber of word lines and/or bit lines. As illustrated, the word lines102-0, 102-1, . . . , 102-N are parallel to each other and areorthogonal to the bit lines 104-0, 104-1, . . . , 104-M, which aresubstantially parallel to each other; however, embodiments are not solimited. The conductive lines can include conductive material, e.g., ametal material. Examples of the conductive material include, but are notlimited to, tungsten, copper, titanium, aluminum, and/or combinationsthereof, among other conductive materials.

Each memory cell 106 may include a memory element, e.g., a resistivememory element, coupled in series with a select device, e.g., an accessdevice, in accordance with a number of embodiments described herein. Thememory element and the select device are discussed further herein.

The select devices can be operated, e.g., turned on/off, toselect/deselect the memory cells 106 in order to perform operations suchas data programming, e.g., writing, and/or data sensing, e.g., readingoperations. In operation, appropriate voltage and/or current signals,e.g., pulses, can be applied to the bit lines and word lines in order toprogram data to and/or read data from the memory cells 106. As anexample, the data stored by a memory cell 106 of array 100 can bedetermined by turning on a select device and sensing a current throughthe memory element. The current sensed on the bit line corresponding tothe memory cell 106 being read corresponds to a resistance level of thememory element, e.g., a resistance level of a resistance variablematerial, which in turn may correspond to a particular data state, e.g.,a binary value. The array 100 can have an architecture other than thatillustrated in FIG. 1, as will be understood by one of ordinary skill inthe art.

The array 100 can be a two dimensional array. For example, the memorycells 106 of the array 100 can be arranged between the access lines,102-0, 102-1, . . . , 102-N and the data/sense lines, 104-0, 104-1, . .. , 104-M in a single level. The array 100 can be a three dimensionalarray. For example, the memory cells of the array can be arranged inmultiple levels, where each of the multiple levels has memory cellsorganized in a cross point architecture. For three dimensional arrayembodiments of the present disclosure, a vertical string of memory cellscan be coupled to a data line and a plurality of access lines coupled tothe vertical string of memory cells, for instance.

The access lines 102-0, 102-1, . . . , 102-N and the data/sense lines104-0, 104-1, . . . , 104-M can be coupled to decoding circuits formedin a substrate material, e.g., formed adjacent to or for example below,the array 100 and used to interpret various signals, e.g., voltagesand/or currents, on the access lines and/or the data/sense lines. As anexample, the decoding circuits may include row decoding circuits fordecoding signals on the access lines, and column decoding circuits fordecoding signals on the data/sense lines.

As used in the present disclosure, the term substrate material caninclude silicon-on-insulator (SOI) or silicon-on-sapphire (SOS)technology, doped and undoped semiconductors, epitaxial layers ofsilicon supported by a base semiconductor foundation, conventional metaloxide semiconductors (CMOS), e.g., a CMOS front end with a metalbackend, and/or other semiconductor structures and technologies. Variouselements, e.g., transistors, and/or circuitry, such as decode circuitryfor instance, associated with operating the array 100 can be formedin/on the substrate material such as via process steps to form regionsor junctions in the base semiconductor structure or foundation.

The memory cells 106 can be formed using various processing techniquessuch as atomic material deposition (ALD), physical vapor deposition(PVD), chemical vapor deposition (CVD), supercritical fluid deposition(SFD), patterning, etching, filling, chemical mechanical planarization(CMP), combinations thereof, and/or other suitable processes. Inaccordance with a number of embodiments of the present disclosure,materials may be grown in situ.

FIG. 2 illustrates a cross-sectional view of a memory cell 206 inaccordance with a number of embodiments of the present disclosure. Asmentioned the memory cell 206 can include a memory element 208. Thememory element 208 can include a programmable portion that may have avariable resistance, for example. The memory element 208 can include,for example, one or more resistance variable materials. Embodimentsprovide that the memory element 208 can be formed on an electrode, e.g.,the memory element can be formed by depositing sequential layers on theelectrode. For example, the memory element 208 can be formed onelectrode material 212-2, as discussed further herein, by physical vapordeposition.

The memory element 208 can include a resistance variable material, e.g.,a phase change material. The resistance variable material can be achalcogenide e.g., a Ge—Sb—Te material such as Ge₂Sb₂Te₅, Ge₁Sb₂Te₄,Ge₁Sb₄Te₇, etc., among other resistance variable materials. Thehyphenated chemical composition notation, as used herein, indicates theelements included in a particular mixture or compound, and is intendedto represent all stoichiometries involving the indicated elements. Otherresistance variable materials can include Ge—Te, In—Se, Sb—Te, As—Te,Al—Te, Ge—Sb—Te, Te—Ge—As, In—Sb—Te, Te—Sn—Se, Ge—Se—Ga, Bi—Se—Sb,Ga—Se—Te, Sn—Sb—Te, Te—Ge—Sb—S, Te—Ge—Sn—O, Te—Ge—Sn—Au, Pd—Te—Ge—Sn,In—Se—Ti—Co, Ge—Sb—Te—Pd, Ge—Sb—Te—Co, Sb—Te—Bi—Se, Ag—In—Sb—Te,Ge—Sb—Se—Te, Ge—Sn—Sb—Te, Ge—Te—Sn—Ni, Ge—Te—Sn—Pd, and Ge—Te—Sn—Pt, forexample.

The memory element 208 can have a thickness 209 of in a range from 10nanometers to 35 nanometers. For example, the memory element 208 canhave a thickness in a range from 12 nanometers to 30 nanometers, or in arange from 15 nanometers to 25 nanometers. For a number of embodiments,the memory element 208 can have a thickness 209 of 20 nanometers.

The memory element 208 can include a number of memory element portions211-1, 211-2, 211-3, 211-4, 211-5. As illustrated in FIG. 2, the memoryelement 208 includes five portions; however, embodiments are not solimited. For example, the memory element 208 can include two, three,four, six, seven, or other numbers of memory element portions. Accordingto a number of embodiments, the memory element portions can correspondto different layers of the memory element.

Embodiments provide that the memory element portions 211-1, 211-2,211-3, 211-4, 211-5 can have the same composition; however, embodimentsare not so limited. For example, each of the memory element portions canhave a different composition. Also, for example, a number of the memoryelement portions can have a first composition while another number ofthe memory element portions have a second composition, such that thefirst composition is different than the second composition.

Each of the memory element portions 211-1, 211-2, 211-3, 211-4, 211-5can have a thickness in a range from 1 nanometer to 10 nanometers. Forexample, the memory element portions can have a thickness in a rangefrom 2 nanometers to 8 nanometers, or from 3 nanometers to 7 nanometers.For a number of embodiments, the memory element portions can have athickness of 5 nanometers. Embodiments provide that the memory elementportions can have the same thickness; however, embodiments are not solimited. For example, each of the memory element portions can have adifferent thickness. Also, for example, a number of the memory elementportions can have a first thickness while another number of the memoryelement portions have a second thickness, such that the first thicknessis different than the second thickness.

The memory cell 206 can include a number of conductive diffusion barriermaterials 210-1, 210-2, 210-3, 210-4 located between a first portion211-1 of the memory element 208 and a second portion 211-2 of the memoryelement 208. According to a number of embodiments, the conductivediffusion barrier materials can correspond to different layers of thememory element. The conductive diffusion barrier material 210 isconductive. The conductive diffusion barrier material 210 can include aninert material, such as carbon, carbon nitride or combinations thereof,among other inert materials. Embodiments provide that the conductivediffusion barrier materials 210 can have the same composition; however,embodiments are not so limited. For example, each of the conductivediffusion barrier materials can have a different composition. Also, forexample, a number of the conductive diffusion barrier materials can havea first composition while another number of the conductive diffusionbarrier materials have a second composition, such that the firstcomposition is different than the second composition. As an example, theinert material can be non-reactive with a chalcogenide. The conductivediffusion barrier material 210 can help prevent electromigration ofcomponents of a phase change material, e.g., a phase change materialcomprised by a memory element as discussed herein, and/or modulate thegrain size of a phase change material included in the memory element208.

As illustrated in FIG. 2, there are four conductive diffusion barriermaterials 210-1, 210-2, 210-3, 210-4 located between the portion 211-1of memory element 208 and the portion 211-2 of memory element 208;however, embodiments are not so limited. For example, there may be one;two, three, five, or other numbers of conductive diffusion barriermaterials 210 located between the portion 211-1 of memory element 208and the portion 211-2 of memory element 208.

Each of the conductive diffusion barrier materials 210 can have athickness in a range from 1 angstrom to 50 angstroms. For example, theconductive diffusion barrier material 210 can have a thickness in arange from 1 angstrom to 40 angstroms, from 1 angstrom to 30 angstroms,from 1 angstrom to 15 angstroms, or from 1 angstrom to 5 angstroms. Forembodiments having a plurality of conductive diffusion barrier materials210, the conductive diffusion barrier materials 210 can have the samethickness; however, embodiments are not so limited. For example, each ofthe conductive diffusion barrier materials 210 can have a differentthickness. Also, for example, a number of the conductive diffusionbarrier materials 210 can have a first thickness while another number ofthe conductive diffusion barrier materials 210 have a second thickness,such that the first thickness is different than the second thickness.

Each of the conductive diffusion barrier materials 210 is immediatelylocated between different portions of the memory element 208. Forexample, the conductive diffusion barrier materials can be interleavedbetween respective memory element portions. In other words, each of theconductive diffusion barrier materials 210 is separated from anotherdiffusion barrier material 210 by at least one portion of the memoryelement 208. For example, as illustrated in FIG. 2, the conductivediffusion barrier material 210-1 that contacts the portion 211-1 ofmemory element 208 is separated from the conductive diffusion barriermaterial 210-4 that contacts the portion 211-2 of memory element 208 bythree portions 211-3, 211-4, 211-5 of memory element 208.

As mentioned, the memory element 208 can be formed on an electrode,e.g., electrode 212-2 discussed below. For example, a portion 211-1 ofmemory element 208 can be formed on electrode 212-2. Thereafter, aconductive diffusion barrier material 210-1 can be formed on the portion211-1 of the memory element 208 and a portion 211-3 can be formed on theconductive diffusion barrier material 210-1. Similarly, additionalportions of the memory element, e.g., portions 211-4, 211-5, 211-2, andadditional conductive diffusion barrier materials, e.g., conductivediffusion barrier materials 210-2, 210-3, 210-4, can be formed. Thememory element 208 can be formed by physical vapor deposition, forexample.

As illustrated in FIG. 2, the memory cell 206 can include a number ofelectrodes, e.g., a first electrode 212-1, a second electrode 212-2, anda third electrode 212-3. Embodiments of the present disclosure providethat an electrode, e.g., electrode 212-1 can be coupled to, e.g., formedon, a conductive line, such as conductive line 202 shown in FIG. 2 orone of conductive lines 102-0 to 102-N shown in FIG. 1. Embodiments ofthe present disclosure provide that an electrode, e.g., electrode 212-3can be coupled to a conductive line, such as conductive line 204 shownin FIG. 2 or one of conductive lines 104-0 to 104-M shown in FIG. 1. Forexample, conductive line 204 can be formed on electrode 212-3, which canbe formed on the memory element 208. Embodiments of the presentdisclosure provide that an electrode, e.g., electrode 212-2 can belocated between the memory element 208 and a select device 214. Forexample, electrode 212-2 can be formed on the select device 214 and thememory element 208 can be formed on the electrode 212-2. The electrodescan be formed by physical vapor deposition, for example.

Embodiments of the present disclosure provide that the conductivediffusion barrier materials 210 are parallel to an electrode, e.g.,electrode 212-1, electrode 212-2, and/or third electrode 212-3. However,embodiments are not so limited.

The electrodes 212-1, 212-2, 212-3 can include an electrode material.Examples of the electrode material include, but are not limited to, Ti,Ta, W, Al, Cr, Zr, Nb, Mo, Hf, B, C, nitrides of the aforementionedmaterials, e.g., TiN, TaN, WN, CN, etc., and/or combinations thereof.

The memory cell 206 can include a select device 214. The select device214 can be located between two electrodes, e.g., electrode 212-1 andelectrode 212-2. For example, the select device 214 can be formed onelectrode 212-1 and electrode 212-2 can be formed on the select device214. As an example, the select device can be formed by depositingsequential layers on the electrode. The select device can be formed byphysical vapor deposition, for example.

In a number of embodiments, the select device 214 can be a two-terminalovonic threshold switch (OTS), for instance. An OTS can include, forexample, a chalcogenide material, as discussed herein, formed between apair of conductive materials, e.g., electrodes 212-1, 212-2. Responsiveto an applied voltage across the OTS that is less than a thresholdvoltage, the OTS can remain in an “off” state, e.g., an electricallynonconductive state. Alternatively, responsive to an applied voltageacross the OTS that is greater than the threshold voltage, the OTS cansnapback to an “on” state. In the “on” state the OTS can carrysubstantial current with a voltage at its terminals remaining almostconstant to a holding voltage level.

FIG. 3 illustrates a cross-sectional view of a memory cell 306 inaccordance with a number of embodiments of the present disclosure. Thememory cell can include a select device 314. The select device cancomprise a select device material. The select device can comprise achalcogenide, e.g., a Ge—Sb—Te material such as Ge₂Sb₂Te₅, Ge₁Sb₂Te₄,Ge₁Sb₄Te₇, etc., among other resistance variable materials. Thehyphenated chemical composition notation, as used herein, indicates theelements included in a particular mixture or compound, and is intendedto represent all stoichiometries involving the indicated elements. Otherresistance variable materials, which the select device 314 can comprise,include Ge—Te, In—Se, Sb—Te, As—Te, Al—Te, Ge—Sb—Te, Te—Ge—As, In—Sb—Te,Te—Sn—Se, Ge—Se—Ga, Bi—Se—Sb, Ga—Se—Te, Sn—Sb—Te, Te—Ge—Sb—S,Te—Ge—Sn—O, Te—Ge—Sn—Au, Pd—Te—Ge—Sn, In—Se—Ti—Co, Ge—Sb—Te—Pd,Ge—Sb—Te—Co, Sb—Te—Bi—Se, Ag—In—Sb—Te, Ge—Sb—Se—Te, Ge—Sn—Sb—Te,Ge—Te—Sn—Ni, Ge—Te—Sn—Pd, and Ge—Te—Sn—Pt.

Embodiments provide that the select device portions can have the samecomposition; however, embodiments are not so limited. For example, eachof the select device portions can have a different composition. Also,for example, a number of the select device portions can have a firstcomposition while another number of the select device portions have asecond composition, such that the first composition is different thanthe second composition.

The select device 314 can have a thickness 315 of in a range from 10nanometers to 35 nanometers. For example, the select device 314 can havea thickness in a range from 12 nanometers to 30 nanometers, or in arange from 15 nanometers to 25 nanometers.

The select device 314 can include a number of select device portions318-1, 318-2, 318-3, 318-4, 318-5. As illustrated in FIG. 3, the selectdevice 314 includes five portions; however, embodiments are not solimited. For example, the select device 314 can include two, three,four, six, seven, or other numbers of memory element portions. Accordingto a number of embodiments, select device portions can correspond todifferent layers of the memory element.

Each of the select device portions 318-1, 318-2, 318-3, 318-4, 318-5 canhave a thickness in a range from 1 nanometer to 10 nanometers. Forexample, the select device portions can have a thickness in a range from2 nanometers to 8 nanometers, or from 3 nanometers to 7 nanometers. Fora number of embodiments, the select device portions can have a thicknessof 5 nanometers. Embodiments provide that the select device portions canhave the same thickness; however, embodiments are not so limited. Forexample, each of the select device portions can have a differentthickness. Also, for example, a number of the select device portions canhave a first thickness while another number of the select deviceportions have a second thickness, such that the first thickness isdifferent than the second thickness.

Embodiments of the present disclosure provide that the memory cell 306can include a number of conductive diffusion barrier materials 316-1,316-2, 316-3, 316-4 located between a first portion 318-1 of the selectdevice 314 and a second portion 318-2 of the select device 314. Theconductive diffusion barrier material 316 can include an inert material,such as carbon or carbon nitride, among other inert materials.Embodiments provide that the conductive diffusion barrier materials 316can have the same composition; however, embodiments are not so limited.For example, each of the conductive diffusion barrier materials can havea different composition. Also, for example, a number of the conductivediffusion barrier materials can have a first composition while anothernumber of the conductive diffusion barrier materials have a secondcomposition, such that the first composition is different than thesecond composition. The conductive diffusion barrier material 316 canhelp to prevent electromigration of components, e.g., a select devicematerial, of the select device 314 and/or modulate the grain size of thephase change material. The number of conductive diffusion barriermaterials can be formed by physical vapor deposition, for example.

As illustrated in FIG. 3, there are four conductive diffusion barriermaterials 316-1, 316-2, 316-3, 316-4 located between the portion 318-1of select device 314 and the portion 318-2 of select device 314;however, embodiments are not so limited. For example, there may be one;two, three, five, or other numbers of conductive diffusion barriermaterials 316 located between the portion 318-1 of select device 314 andthe portion 318-2 select device 314.

Each of the conductive diffusion barrier materials 316 can have athickness in a range from 1 angstrom to 50 angstroms. For example, theconductive diffusion barrier material 316 can have a thickness in arange from 1 angstrom to 40 angstroms, from 1 angstrom to 30 angstroms,from 1 angstrom to 15 angstroms, or from 1 angstrom to 5 angstroms. Forembodiments having a plurality of conductive diffusion barrier materials316, the conductive diffusion barrier materials 316 can have the samethickness; however, embodiments are not so limited. For example, each ofthe conductive diffusion barrier materials 316 can have a differentthickness. Also, for example, a number of the conductive diffusionbarrier materials 316 can have a first thickness while another number ofthe conductive diffusion barrier materials 316 have a second thickness,such that the first thickness is different than the second thickness.

Each of the conductive diffusion barrier materials 316 is immediatelylocated between different portions of the select device 314. Forexample, the conductive diffusion barrier materials can be interleavedbetween respective select device portions. In other words, each of theconductive diffusion barrier materials 316 is separated from anotherdiffusion barrier material 316 by at least one portion of the selectdevice 314. For example, as illustrated in FIG. 3, the conductivediffusion barrier material 316-1 that contacts the portion 318-1 ofselect device 314 is separated from the conductive diffusion barriermaterial 316-4 that contacts the portion 318-2 of select device 314 bythree portions 318-3, 318-4, 318-5 of select device 314.

Embodiments of the present disclosure provide that the conductivediffusion barrier materials 316 are parallel to an electrode, e.g.,electrode 312-1, electrode 312-2, and/or third electrode 312-3. However,embodiments are not so limited.

FIG. 4 illustrates a cross-sectional view of a memory cell 406 inaccordance with a number of embodiments of the present disclosure. Asillustrated in FIG. 4, embodiments of the present disclosure providethat a memory cell 406 can include a number of conductive diffusionbarrier materials 410-1, 410-2, 410-3, 410-4 located between a firstportion 411-1 of the memory element 408 and a second portion 411-2 ofthe memory element 408 and a number of conductive diffusion barriermaterials 416-1, 416-2, 416-3, 416-4 located between a first portion418-1 of the select device 414 and a second portion 418-2 of the selectdevice 414.

Embodiments of the present disclosure provide that the memory cell canhave a dimension, e.g., a diameter or a width, in range from 10nanometers to 30 nanometers. For example, the memory cell can have adimension in range from 15 nanometers to 25 nanometers. For a number ofembodiments, the memory cell can have a dimension of 20 nanometers.

A number of embodiments provide that a memory cell having a dimension ofa greater value, relative to a memory cell having a dimension of alesser value, can include a greater number of conductive diffusionbarrier materials located between a first portion of a memory elementand a second portion of the memory element as compared to the memorycell having the dimension of a lesser value. For example, a memory cellhaving a diameter of 20 nanometers can include a greater number ofconductive diffusion barrier materials, e.g., four conductive diffusionbarrier materials, located between a first portion of a memory elementand a second portion of the memory element as compared to a memory cellhaving a diameter of 15 nanometers, which can include three conductivediffusion barrier materials located between a first portion of a memoryelement and a second portion of the memory element. However, embodimentsare not so limited.

A number of embodiments provide that a memory cell having a dimension ofa greater value, relative to a memory cell having a dimension of alesser value, can include a greater number of conductive diffusionbarrier materials located between a first portion of a select device anda second portion of the select device as compared to the memory cellhaving the dimension of a lesser value. For example, a memory cellhaving a diameter of 20 nanometers can include a greater number ofconductive diffusion barrier materials, e.g., four conductive diffusionbarrier materials, located between a first portion of a memory elementand a second portion of the select device as compared to a memory cellhaving a diameter of 15 nanometers, which can include three conductivediffusion barrier materials located between a first portion of a memoryelement and a second portion of the select device. However, embodimentsare not so limited.

Although specific embodiments have been illustrated and describedherein, those of ordinary skill in the art will appreciate that anarrangement calculated to achieve the same results can be substitutedfor the specific embodiments shown. This disclosure is intended to coveradaptations or variations of various embodiments of the presentdisclosure. It is to be understood that the above description has beenmade in an illustrative fashion, and not a restrictive one. Combinationof the above embodiments, and other embodiments not specificallydescribed herein will be apparent to those of skill in the art uponreviewing the above description. The scope of the various embodiments ofthe present disclosure includes other applications in which the abovestructures and methods are used. Therefore, the scope of variousembodiments of the present disclosure should be determined withreference to the appended claims, along with the full range ofequivalents to which such claims are entitled.

What is claimed is:
 1. A method of forming a memory cell, the methodcomprising: forming a number of select device materials and a number ofmemory element materials between a first electrode and a secondelectrode; interleaving a number of conductive diffusion barriermaterials with at least one of: the number of select device materials;and the number of memory element materials; and separating a first ofthe number of conductive diffusion barrier materials from a second ofthe number of conductive diffusion barrier materials by at least one ofa second select device material and a second memory element material. 2.The method of claim 1, wherein each of the number of conductivediffusion barrier materials have a thickness in a range from 1 angstromto 50 angstroms.
 3. The method of claim 1, wherein the number ofconductive diffusion barrier materials comprises carbon, carbon nitride,or a combination thereof.
 4. The method of claim 1, wherein interleavingthe number of conductive diffusion barrier materials comprisesinterleaving the number of conductive diffusion barrier materials withthe number of select device materials to form a select device.
 5. Themethod of claim 4, wherein the number of select device materials form anovonic threshold switch.
 6. The method of claim 1, wherein interleavingthe number of conductive diffusion barrier materials comprisesinterleaving the number of conductive diffusion barrier materials withthe number of memory element materials to form a programmable memorydevice.
 7. The method of claim 1, wherein a first portion of the numberof conductive diffusion barrier materials have a first thickness and asecond portion of the number of conductive diffusion barrier materialshave a second thickness that is different than the first thickness. 8.The method of claim 1, wherein each the number of conductive diffusionbarrier materials have a different thickness.
 9. The method of claim 1,wherein each the number of conductive diffusion barrier materials have asame thickness.
 10. The method of claim 1, wherein the number of memoryelements comprises a chalcogenide material.
 11. The method of claim 1,wherein each of the number of conductive diffusion barrier materials isparallel to the first electrode and the second electrode.